T-Cell Receptor Gene Rearrangement
Also known as:T-cell Gene Clonality; TCGR; TCR Gene Rearrangement
Formal name:T-Cell Receptor Gene Rearrangement
Related tests:Complete Blood Count, White Blood Cell Differential, Blood Smear, Immunophenotyping, Chromosome Analysis, Bone Marrow Aspiration and Biopsy, B-cell Immunoglobulin Gene Rearrangement
Why Get Tested?
To help diagnose a T-cell lymphoma; sometimes to detect and evaluate residual cancer cells
When to Get Tested?
When a doctor thinks that you may have a T-cell lymphoma; when a doctor would like to assess whether treatment has been effective and/or whether lymphoma has recurred
A bone marrow, tissue such as a lymph node (biopsy), or body fluid sample collected by your doctor; sometimes a blood sample drawn from a vein in your arm
Test Preparation Needed?
How is it used?
T-cell receptor gene rearrangement testing is used to help diagnose T-cell lymphomas and to evaluate for residual or recurrent disease after treatment.
Lymphomas arise when an abnormal T-cell begins to produce numerous identical copies of itself (clones). The cloned cells grow and divide uncontrollably, crowding out normal cells. There are many different types of T-cell lymphoma and each has different characteristics, prognosis, and a likely response to therapy. Several classification systems have been used to describe them. The most recent is the World Health Organization's. (For more on this, see the Lymphoma page.)
Testing for T-cell lymphomas is done in a step-wise fashion and typically starts with:
- Complete Blood Count (CBC) and a WBC differential to evaluate the number, types, and maturity of white blood cells present in the blood. Results may reveal an increased number of lymphocytes and/or presence of abnormal lymphocytes.
- A pathology evaluation of blood smear, bone marrow, lymph node, skin and/or other tissue biopsy samples is performed. These samples are examined under a microscope by a trained laboratorian, usually a pathologist.
- If indicated, immunophenotyping is performed on blood, bone marrow, or other tissue (such as an enlarged lymph node or tumor) using a method such as flow cytometry or immunohistochemistry. This test detects the presence or absence of certain markers on the membrane of the cells or inside the cells. These commonly used markers are called clusters of differentiation (CD) and are listed numerically. Patterns of antigens (presence or absence) can provide information as to whether the T-cells are clones (monoclonal) and can further help classify a T-cell lymphoma.
A proliferation of T-cells can be benign or malignant. If, after the above tests are performed, there is still no conclusion as to whether a person has a benign or malignant T-cell population, a T-cell receptor gene rearrangement test can be performed.
Testing may sometimes be performed to evaluate the effectiveness of lymphoma treatment - to detect residual or recurrent disease, the continued presence of abnormal monoclonal T-cells.
When is it ordered?
Testing is performed when a person has signs and symptoms that suggest a lymphoma, such as:
- One or more swollen but painless lymph nodes–depending on the site of the affected lymph node, symptoms may involve areas of the chest, armpit, neck, abdomen, or groin area, for example.
- Skin lesions
- Enlarged spleen and/or liver
- Night sweats
- Unexplained weight loss
- Neurologic symptoms that may suggest central nervous system involvement
Testing may be done when other laboratory tests indicate that a lymphoma may be present and/or when other tests are inconclusive. Some examples include:
- An increased number of lymphocytes, especially abnormal-looking lymphocytes, as determined with a CBC and a blood smear examination
- Signs of lymphoma in a tissue biopsy, body fluid or bone marrow sample
- With immunophenotyping (e.g., flow cytometry, immunohistochemistry), antigen groupings that are inconclusive for a T-cell lymphoma, or when the doctor wants to confirm a diagnosis of lymphoma based on histopathology and immunophenotyping
Testing may also be ordered when a person has been treated for a lymphoma to evaluate the effectiveness of treatment and to detect residual or recurrent disease.
What does the test result mean?
Results of testing are typically interpreted by a doctor who specializes in pathology, in particular, pathology dealing with blood, blood cells, and bone marrow cells (hematopathology). Results must be interpreted in conjunction with clinical findings, other test results including histopathology, immunophenotyping information, an understanding of the strengths and limitations of different testing methods, and with an understanding of the range of findings that can be found in a "normal" lymphocyte cell population.
This testing helps confirm whether a cloned population of T-cell lymphocytes is present and helps confirm and/or clarify a person's diagnosis. In general, if a significant clonal T-cell population is detected and other associated tests are in agreement, it is likely that the individual tested has a T-cell lymphoma or that lymphoma has recurred.
Examples of lymphomas that may be detected by this testing include:
- Adult T-cell leukemia/lymphoma (ATLL)
- Anaplastic large-cell lymphoma
- Angioimmunoblastic T-cell lymphoma
- Enteropathy-associated T-cell lymphoma
- Hepatosplenic T-cell lymphoma
- Mycosis fungoides
- Peripheral T-cell lymphoma, unspecified
- Precursor T-cell neoplasm (T lymphoblastic leukemia/lymphoma)
- Sezary syndrome
- T-cell large granular lymphocytic leukemia
- T-cell prolymphocytic leukemia
Is there anything else I should know?
According to the American Cancer Society (ACS), non-Hodgkin lymphoma (NHL) is one of the most common cancers in the United States. ACS estimates that about 70,130 people will be diagnosed with NHL in 2012 and as many as 18,940 will die of it. The majority of these cases (about 85%) will be due to B-cell lymphomas; close to 15% will be T-cell lymphomas.
Testing may need to be repeated when the sample does not contain enough DNA to test or if the sample is not suitable for testing.
The detection of a clonal T-cell receptor gene rearrangement is not synonymous with the presence of T-cell lymphoma. An individual may have a clonal T-cell population and not have cancer. Conditions such as autoimmune disorders, certain infections, immune suppression, and immune deficiencies are sometimes associated with small clonal T-cell populations. This means that one or more groups of cloned T-cells may be present in a person's lymphocyte population without it being considered a lymphoma.
If a person is negative for a clonal T-cell receptor gene rearrangement, the person may still have lymphoma. A test may also be negative if the test method is not sensitive enough to detect the rearrangement or if the clonal lymphocytes from the person tested have mutations that are not detected by the test, or if the lymphoma is of the B-cell type.
Since false positive and false negative results can be associated with the testing, the results must be interpreted in the context of other clinical and pathologic findings.
What is being tested?
This test detects characteristic changes (rearrangements) in specific genes in T-cells. This information can be helpful in diagnosing a T-cell lymphoma.
T-cells are a type of lymphocyte (a kind of white blood cell, WBC) that helps to protect the body from infection. Rearrangements in certain parts of their DNA called receptor genes are a normal part of their development. These rearrangements are associated with the development of a large repertoire of diverse T-cells, allowing them to protect against many different kinds of infections. The final order in which the genes are rearranged is called a gene rearrangement profile. Within any normal population (sample) of T-cells, the cells and their gene rearrangement profiles are very diverse.
In lymphoma, the T-cells in affected tissue (such as blood, lymph node, or skin) are identical and their gene rearrangement profiles are likewise identical. Lymphomas arise when an abnormal T-cell begins to produce numerous identical copies of itself (clones). The cloned cells grow and divide uncontrollably, crowding out normal cells.
A T-cell receptor gene rearrangement test evaluates the T-cells in a person's sample to determine whether the majority of T-cell rearrangement profiles are diverse or identical. This information, along with clinical signs and symptoms and results of other laboratory tests, can help clarify a person's diagnosis, or evaluate for persistent or recurrent lymphoma.
Most non-Hodgkin lymphomas in the U.S. are B-cell lymphomas (about 85%), according to the American Cancer Society. Close to 15% are T-cell lymphomas. There are many different types of T-cell lymphomas, but each is rare.
For additional details about T-cells and this testing, read more.
How is the sample collected for testing?
A bone marrow, lymph node, or other tissue biopsy procedure is performed by a doctor or other trained specialist. Body fluid samples are obtained through collection of the fluid in a container by inserting a needle into the body cavity and aspirating a portion of the fluid with a syringe. Sometimes, a blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
- Should everyone with a T-cell lymphoma have T-cell receptor gene rearrangement testing?
No. This testing is required only if routine diagnostic procedures are insufficient to make an accurate diagnosis.
- Can results of testing be used to determine the course of my cancer (prognosis)?
No. A positive testing result only helps to confirm a diagnosis of T-cell lymphoma. The cancer progression and response to treatment is generally determined by the type of a person's lymphoma, but will also vary from person to person.
- Where is T-cell receptor gene rearrangement testing performed?
This testing requires specialized equipment and interpretation. It is not offered by every laboratory and samples will often need to be sent to a reference laboratory.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
Descriptions of clinical laboratory tests were originally prepared for use on Lab Tests Online, an award-winning patient education website on clinical laboratory testing. Lab Tests Online is produced by the American Association for Clinical Chemistry (AACC), a global scientific and medical professional organization dedicated to clinical laboratory science and its application to healthcare. The Lab Tests Online website is developed in collaboration with other laboratory professional societies and is funded in part through corporate sponsorships.